The present invention generally relates to medical catheters, more particularly to medical catheters wherein the elongated shaft of the catheter includes a helically wound coil component which provides the principal structural integrity of the catheter shaft at that location which enables it to perform as a catheter, including needed torsional rigidity and kink resistance. At the same time, the helically wound coil provides a structure which is extremely flexible in order to facilitate maneuvering during use, even through highly tortuous vessels of the body. A thin polymeric skin generally extends along the helically wound coil without substantially affecting the strength or maneuverability characteristics of the helically wound coil itself, such as its resistance to axially directed forces.
Numerous catheter types and styles are known and/or used for any number of various medical procedures. Included are catheters for angioplasty procedures, including catheters incorporating so-called balloon components, other catheters for delivering medication or treatment or means for observation, analysis, detection and the like, as well as other catheter structures such as catheter sheath introducers. Often these catheter devices have a substantially small outer diameter. Typically, catheters for percutaneous transluminal coronary angioplasty procedures are of this small diameter variety. It is often necessary that catheters wind their way through various passageways within the human body, such as coronary passageways and branched veins. When balloon catheters are involved, it is at times necessary to have the balloon catheter exhibit a combination of torsional control and flexibility which permits and facilitates placement of the balloon at the precisely needed location in a very efficient and accurate manner. Because of the extremely small locations into which devices of this type are passed, it is often a primary objective to have the catheters exhibit extremely thin wall characteristics.
Heretofore, various catheter devices have been provided which exhibit particularly advantageous torsional rigidity and axial strength properties. Often these catheters achieve an especially thin-walled structure by being made of polymers having excellent torsional rigidity properties which are imparted to the catheter even when the polymeric catheter wall is especially thin. At times, catheters incorporate braiding to enhance the torsional control properties of the catheter. Generally helically shaped coils have also been used in an effort to attain these ends and objectives. When such braids or coils are used, they will usually serve to assist the structural properties of the cylindrical catheter shaft, often being embedded within the polymeric catheter shaft.
Typically, catheter shafts or devices which incorporate braids or helical coils achieve enhanced torsional control at the expense of flexibility of the type that enhances the maneuverability of the catheter. Wall thinness usually is also sacrificed. In some instances, these drawbacks are perfectly acceptable. However, in other circumstances, flexibility is the principal objective of the catheter or catheter component. There is a need for a catheter construction which can be tailored to meet especially stringent flexibility criteria and move through highly tortuous paths within the body while still providing torsional rigidity that is adequate for catheter use and also superior kink resistance, all without requiring an undesirable wall thickness.
In summary, the present invention provides catheter construction characteristics which exhibit exceptional flexibility and kink resistance while retaining adequate torsional control in order to provide a catheter shaft or body component that imparts maneuverability characteristics which are particularly advantageous for certain specific needs such as movement through tortuous body paths. Included is a shaft length constructed of a helically wound coil having a plurality of windings that are spaced apart from each other as wound. A polymer skin spans the windings and its function is primarily for the purpose of providing a barrier to fluids or liquids which is generally co-extensive with the cylinder defined by the helically wound coil. The skin is substantially thinner and less rigid than the helically wound coil and contributes negligibly to resistance of the catheter to axially directed forces.
It is a general object of the present invention to provide an improved catheter exhibiting exceptional flexibility while retaining adequate torsional control.
Another object of the present invention is to provide an improved angioscopic balloon catheter having an elongated shaft component made of a helically wound coil with a skin spanning adjacent windings without detrimentally affecting the mechanical properties of the coil.
Another object of this invention is to provide an improved catheter construction having a catheter shaft with helically coiled windings that are spaced from each other as wound and that vary such spacing when used.
Another object of the present invention is to provide a helically wound catheter made of a coil having a thin skin spanning coil windings but neither contributing substantially to catheter wall thickness nor contributing any significant resistance to compressive axial movement of the catheter shaft.
These and other objects, features and advantages of this invention will be clearly understood through a consideration of the following detailed description.